Multi-parameter cardiac magnetic resonance imaging detects anthracycline-induced cardiotoxicity in rabbits model.

Background: Cardiac magnetic resonance (CMR) quantitative T1 and T2 mapping offers a non-invasive means to evaluate early cardiotoxicity changes. This study aimed to pinpoint the earliest CMR indicators of myocardial injury in Anthracycline-induced cardiotoxicity (AIC) and to elucidate the connections between these CMR indicators and associated pathological indicators. Methods: A total of 34 rabbits were administered doxorubicin at a dosage of 1 mg/kg/weekly. The study incorporated six 3T CMR scan time points: baseline, and at intervals of four, six, eight, twelve, and sixteen weeks. Cine, T1 and T2 mapping sequences assessed the left ventricular ejection fraction (LVEF), native T1, extracellular volume fraction (ECV), and T2 values. Following each time point, three rabbits were sacrificed for histological analysis involving Hematoxylin and eosin (H&E), Masson, TUNEL, and microvascular density (MVD) stains. Spearman correlations and linear mixed model analysis served in the statistical analysis. Results: Diverse degrees of alternation were recorded in LVEF, native T1, T2, and ECV over time. LVEF declined to 49.0 ± 2.6 % at 12 weeks from the baseline of 53.4 ± 3.2 %, p < 0.001. Native T1 values increase from the baseline (1396.5 ± 79.2 ms) until 8 weeks (1498.8 ± 95.4 ms, p < 0.001). T2 values increased from the baseline (36.6 ± 3.3 ms) within 4 weeks of initiation (37.5 ± 3.4, p = 0.02) and remained elevated through 16 weeks (42.8 ± 0.3, p < 0.01). ECV was elevated at 8 weeks (33.9 ± 3.8 %, p = 0.005) compared to the baseline (30.2 ± 2.5 %). By week 12, myocardial edema and increased CVF were apparent (p = 0.04 and = 0.001, respectively). The area under ROC curve for positive CMR presence and the gold standards were 0.87 (T2-ROC, 4 weeks) and 0.92 (LVEF&BNP-ROC, 12 weeks). Conclusion: T1 and T2 mapping are effective tools for cardiotoxicity detection and monitoring. The prolongation of T2 value emerged as the most consistent and early-onset indicator.

Histologic validation of stress cardiac magnetic resonance T1-mapping techniques for detection of coronary microvascular dysfunction in rabbits.

BACKGROUND: To investigate the diagnostic performance of stress cardiac magnetic resonance (CMR) T1-mapping for the detection of coronary microvascular dysfunction (CMD) by correlating microvascular density (MVD) and collagen volume fraction (CVF) with T1 response to adenosine triphosphate (ATP) stress (stress ΔT1) in rabbits. METHODS: Twenty-four New Zealand white rabbits were randomly divided into the CMD group induced by microembolization spheres (n = 10), sham-operated group (n = 5), and control group (n = 9). All rabbits underwent 3.0 T CMR, both rest and ATP stress T1-maps were obtained, and first-pass perfusion imaging was performed. Stress ΔT1 and myocardial perfusion reserve index (MPRI) were calculated. For the histologic study, each rabbit was sacrificed after CMR scanning. Left ventricular myocardial tissue was stained with Hematoxylin-eosin (H&E), Masson, and CD31, from which MVD and CVF were extracted. Pearson correlation analyses were performed to determine the strength of the association between the stress ΔT1 and both MVD and CVF. RESULTS: The stress ΔT1 values (CMD, 2.53 ± 0.37% vs. control, 6.00 ± 0.64% vs. Sham, 6.07 ± 0.97%, p < 0.001) and MPRI (CMD, 1.45 ± 0.13 vs. control, 1.94 ± 0.23, vs. sham, 1.89 ± 0.15, p < 0.001) were both lower in CMD rabbits compared with sham-operated and control rabbits. Further, the stress ΔT1 showed a high correlation with CVF (r = -0.806, p < 0.001) and MVD (r = 0.920, p < 0.001). CONCLUSIONS: Stress T1 response strongly correlates with pathological MVD and CVF, indicating that stress CMR T1 mapping can accurately detect microvascular dysfunction.

Linear late gadolinium enhancement in the basal anterior septum and lateral wall may represent the contrast enhancement of vessels: A CMR and CCTA comparison study.

BACKGROUND: The purpose of this paper was to verify that the linear high-intensity signal on late gadolinium enhancement-cardiac magnetic resonance (LGE-CMR) may represent the contrast enhancement of vessels rather than scars or fibrosis, and to assess whether this linear high-intensity signal will affect the quantification of myocardial fibrosis in patients with hypertrophic cardiomyopathy (HCM). METHODS: A total of 58 patients who underwent both coronary computed tomography angiography (CCTA) and LGE-CMR in our hospital were ultimately enrolled. The definitions of positive linear LGE (LLGE+) were as follows: (1) LLGE in the basal anterior septum or lateral wall, and (2) LLGE observable at 10 mm or more. All other patients were regarded as negative LLGE (LLGE-). In LLGE+ patients, the length of the LLGE located in the anterior septum and lateral wall was compared with the length of the septal perforator artery and the circumflex artery on CCTA, respectively. For nine patients with HCM, the LGE% was measured before and after removal of LLGE. RESULTS: Among the 58 patients, 40 showed LLGE+ and 18 showed LLGE-. For patients with LLGE in the anterior septum, there was a strong correlation between LLGE and anterior septal perforator arteries in length (r=0.887, p<0.001). For patients with LLGE in the lateral wall, LLGE also correlated well with the circumflex arteries in length (r=0.962, p<0.001). In nine patients with HCM, the LGE% decreased significantly after the removal of LLGE [9.50 (7.70 - 17.35)% vs. 8.80 (6.20 - 15.55)%, p<0.05]. CONCLUSIONS: The LLGE in the anterior septum and lateral wall may represent contrast enhancement of the anterior septal perforator artery and the circumflex artery, respectively. This LLGE may overestimate the extent of myocardial fibrosis in patients with HCM.

Stress CMR T1-mapping technique for assessment of coronary microvascular dysfunction in a rabbit model of type II diabetes mellitus: Validation against histopathologic changes.

Background: Coronary microvascular dysfunction (CMD) is an early character of type 2 diabetes mellitus (T2DM), and is indicative of adverse events. The present study aimed to validate the performance of the stress T1 mapping technique on cardiac magnetic resonance (CMR) for identifying CMD from a histopathologic perspective and to establish the time course of CMD-related parameters in a rabbit model of T2DM. Methods: New Zealand white rabbits (n = 30) were randomly divided into a control (n = 8), T2DM 5-week (n = 6), T2DM 10-week (n = 9), and T2DM 15-week (n = 7) groups. The CMR protocol included rest and adenosine triphosphate (ATP) stress T1-mapping imaging using the 5b(20b)3b-modified look-locker inversion-recovery (MOLLI) schema to quantify stress T1 response (stress ΔT1), and first-pass perfusion CMR to quantify myocardial perfusion reserve index (MPRI). After the CMR imaging, myocardial tissue was subjected to hematoxylin-eosin staining to evaluate pathological changes, Masson trichrome staining to measure collagen volume fraction (CVF), and CD31 staining to measure microvascular density (MVD). The associations between CMR parameters and pathological findings were determined using Pearson correlation analysis. Results: The stress ΔT1 values were 6.21 ± 0.59%, 4.88 ± 0.49%, 3.80 ± 0.40%, and 3.06 ± 0.54% in the control, T2DM 5-week, 10-week, and 15-week groups, respectively (p < 0.001) and were progressively weakened with longer duration of T2DM. Furthermore, a significant correlation was demonstrated between the stress ΔT1 vs. CVF and MVD (r = -0.562 and 0.886, respectively; p < 0.001). Conclusion: The stress T1 response correlated well with the histopathologic measures in T2DM rabbits, indicating that it may serve as a sensitive CMD-related indicator in early T2DM.